Recently, there is a growing need for a fuel injection device that can inject a high-pressure fuel. Hence, the fuel pressure in a fuel passage tends to increase during use of the fuel injection device. In a fuel injection device described in Patent Document 1, a nozzle holder configuring part of a housing is press-fitted in a stationary core. The stationary core is joined by welding to the nozzle holder at a press-fitting position. The nozzle holder has a magnetic throttle part having a small thickness portion. The magnetic throttle part is press-fitted in the stationary core and is joined by welding to the stationary core.
In the fuel injection device of Patent Document 1, when the fuel pressure in a fuel passage in the device increases, a force, by which the stationary core separates from the nozzle holder in an axial direction, acts on a welded portion of the stationary core and the nozzle holder or on the thin magnetic throttle part. If the fuel pressure in the fuel passage in the device excessively increases, stress is concentrated on the welded portion of the stationary core and the nozzle holder or the magnetic throttle part, and thus the welded portion or the magnetic throttle part may be broken due to the stress concentration. If the welded portion or the magnetic throttle part is broken, the fuel in the fuel passage may leak to the outside. Consequently, the fuel injection device of Patent Document 1 is structurally difficult to inject high-pressure fuel.
In the fuel injection device of Patent Document 1, when the fuel pressure in the fuel passage in the device excessively increases, a position of the magnetic throttle part with respect to the stationary core is shifted in the axial direction, and the magnitude of magnetic attractive force, which is generated between the stationary core and the movable core, may be varied. This may reduce fuel injection accuracy.